WO2006077864A1

WO2006077864A1 - Method for producing light-emitting body, light-emitting body and light-emitting device

Info

Publication number: WO2006077864A1
Application number: PCT/JP2006/300610
Authority: WO
Inventors: Jiro Kanamori; Yoshisada Hayashi
Original assignee: T. Chatani & Co., Ltd.
Priority date: 2005-01-19
Filing date: 2006-01-18
Publication date: 2006-07-27
Also published as: US20090033229A1; EP1860171A1; JP2006199794A; KR20070095421A; CN101107341A

Abstract

Disclosed is a method for producing a light-emitting body having high luminance and long life. Also disclosed are a light-emitting body and a light-emitting device, specifically an inorganic EL device wherein a backside electrode, a dielectric layer, a light-emitting layer, a dielectric layer and a transparent electrode are sequentially arranged in this order. The light-emitting body is produced by mixing an activator containing Pr, Mn and Au into strontium sulfide (SrS) as the host material, heating the resulting for activating the host material, and then adding GaAs and InP thereinto and firing the resulting in a nitrogen atmosphere containing a sulfur gas. A light-emitting layer can be obtained by mixing the thus-produced light-emitting body with a ultraviolet-curable dielectric substance.

Description

Specification

Method for manufacturing light emitter, light emitter, and light emitting device

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing a light emitter using a rare earth sulfide as a base material, a light emitter, and a light emitting device using the light emitter.

Background art

[0002] Electric-mouth luminescence elements (hereinafter referred to as EL elements) are light-emitting elements that utilize a light-emitting phenomenon that occurs when an electric field is applied to a substance. An organic substance such as an aluminum quinolinol complex is used as a base material. The organic EL elements are roughly classified into inorganic EL elements that are based on inorganic materials such as ZnS and SrS. Among these, inorganic EL elements have superior durability compared to organic EL elements and can reduce power consumption. Therefore, they can be applied to lighting devices such as backlights, night lights, and emergency lights for liquid crystal display devices. Is expected.

[0003] As an inorganic EL element using ZnS as a base material, a device in which a trace amount of Mn is added to a base material or a trace amount of Cu or C1 is known. The former is yellow-orange, The latter has been confirmed to emit blue-green light (for example, see Patent Document 1). In addition, inorganic EL elements using SrS as a base material are known in which a small amount of Ce is added to the base material, and it has been confirmed to emit blue-green light.

Patent Document 1: Japanese Patent Laid-Open No. 2002-241753

Disclosure of the invention

Problems to be solved by the invention

However, since the conventional inorganic EL element has low emission luminance, it can be applied to the backlight, overnight light, emergency light, etc. of the liquid crystal display device as described above when considering practical aspects. It has the problem of being difficult. For example, in a liquid crystal display device, light is absorbed by liquid crystal molecules, phosphors, polarizing plates, etc., and the intensity of light is reduced to about 10% of the original, so that a back light having an emission luminance of at least several thousand cdZm ^{2 is obtained.} A light is requested. However, even the relatively high-intensity inorganic EL element described in Patent Document 1 has an emission luminance of about 500 cd / m ² , and at present, inorganic EL elements are used. Therefore, it has been difficult to produce a liquid crystal display device having sufficient brightness for practical use.

[0005] Although it is possible to increase the emission luminance by increasing the voltage applied to the inorganic EL element, the lifetime of the inorganic EL element (that is, the half-life of EL emission) decreases in proportion to the applied voltage. Therefore, the development of a light-emitting device that can obtain high-intensity light emission without reducing the half-life of EL light emission is desired.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a light emitter capable of manufacturing a high-luminance light emitter, and a high-luminance light emitter.

[0007] Another object of the present invention is to provide a light-emitting device that can emit light with high luminance and can achieve a long life.

Means for solving the problem

[0008] A method for manufacturing a light emitter according to a first aspect of the present invention is a method for manufacturing a light emitter using rare earth sulfide as a base material, comprising the base material, Pr, Mn, and Au, and activating the base material A mixture with an activator is produced, and the produced mixture is heated to activate the base material.

[0009] In the first invention, a mixture of a base material made of rare earth sulfide and an activator containing Pr, Mn, and Au is generated, and the resulting mixture is heated to activate the base material By doing so, a light emitter with high light emission luminance can be obtained.

[0010] The method for manufacturing a light emitter according to the second invention is the method for manufacturing a light emitter according to the first invention.

The rare earth sulfide is SrS.

[0011] In the second invention, a mixture of a matrix material composed of SrS and an activator containing Pr, Mn, and Au is produced, and the resulting mixture is heated to activate the matrix material. , 30

A light emitter having a luminance of about OOcd / m ² is obtained.

[0012] A method for manufacturing a light emitter according to a third invention is the method for manufacturing a light emitter according to the first invention or the second invention, wherein the base material is activated and then added with GaAs and InP, and sulfur is added. It is characterized by firing at a temperature of 798 ° C or higher in a nitrogen atmosphere containing gas.

In the third invention, after activating the base material, GaAs and InP are added, and firing is performed at a temperature of 798 ° C. or higher in a nitrogen atmosphere containing sulfur gas. A luminous body having a luminance of about / m ² is obtained. [0014] A light emitter according to a fourth invention is characterized in that, in a light emitter using a rare earth sulfide as a base material, Pr, Mn, and Au are added to the base material.

In the fourth invention, light emission with high luminance can be obtained by adding Pr, Mn, and Au to the base material made of rare earth sulfide.

[0016] A light emitter according to a fifth invention is the light emitter according to the fourth invention, wherein the rare earth sulfide is

, SrS.

In the fifth invention, emission luminance of about 3000 cd / m ² can be obtained by adding Pr, Mn, and Au to the base material made of SrS.

[0018] A light emitter according to a sixth invention is the light emitter according to the fourth invention or the fifth invention, characterized in that GaAs and InP are further added.

In the sixth invention, by adding GaAs and InP, 4500 cd

An emission luminance of about / m ² can be obtained.

[0020] A light-emitting device according to a seventh invention is characterized by comprising the light-emitting body according to any one of the fourth to sixth inventions, and means for applying an alternating voltage to the light-emitting body.

[0021] In the seventh invention, high luminance light emission is achieved by comprising the light emitter described in the fourth to sixth inventions and means for applying an AC voltage to the light emitter. Is obtained

It will function as various light sources.

[0022] A light-emitting device according to an eighth invention is the light-emitting device according to the seventh invention, further comprising means for controlling the magnitude of the AC voltage so as to make the light emission intensity of the light emitter constant. And

[0023] In the eighth invention, since the AC voltage to be applied to the light emitter is controlled in order to make the light emission intensity constant, high luminance light emission and long life can be realized.

[0024] A light emitting device according to a ninth invention is the light emitting device according to the seventh invention, wherein the light emitting device according to the seventh invention is applied to the light emitter based on the light emission intensity measured by the means and the light emission intensity measured by the light emitter. And means for controlling the magnitude of the alternating voltage to be provided.

[0025] In the ninth invention, since the configuration is such that the means for measuring the light emission intensity of the light emitter and the magnitude of the AC voltage to be applied to the light emitter are controlled based on the measured light emission intensity, Light emission and longer life are realized. The invention's effect

[0026] In the case of the first invention, a mixture of a base material made of a rare earth sulfide and an activator containing Pr, Mn, and Au is generated, and the base material is activated by heating the generated mixture. The illuminant manufactured in this way has higher brightness and light emission brightness than conventional inorganic EL materials, and can be applied to backlights, emergency lights, overnight lights, etc. of liquid crystal display devices. Become.

[0027] In the case of the second invention, a mixture of a base material composed of SrS and an activator containing Pr, Mn, and Au is generated, and the generated mixture is heated to activate the base material. The luminous body manufactured in this way has a luminance of about 3000 cd / m ² and can be used as a backlight of a liquid crystal display device, for example.

[0028] In the case of the third invention, after activating the base material, GaAs and InP are added and baked at a temperature of 798 ° C or higher in a nitrogen atmosphere containing sulfur gas. The light-emitting body thus manufactured has a luminance of about 4500 cd / m ² and can be used as a backlight of a liquid crystal display device, for example.

[0029] In the case of the fourth invention, Pr, Mn, and Au are added to the base material made of rare earth sulfide. Such a light emitter has higher emission brightness than conventional inorganic EL materials, and can be applied to backlights, emergency lights, all-night lights, etc. of liquid crystal display devices.

[0030] In the case of the fifth invention, Pr, Mn, and Au are added to the base material made of SrS. Such a light-emitting body can be used as, for example, a backlight of a liquid crystal display device because it can emit light having a luminance of about 3000 cd / m ² .

[0031] In the case of the sixth invention, GaAs and InP are further added. Such a light-emitting body can be used as a backlight of a liquid crystal display device, for example, because it can obtain a light emission luminance of about 4 500 cd / m ² .

[0032] According to the seventh invention, there is provided the light emitter described in the fourth to sixth inventions, and means for applying an alternating voltage to the light emitter. Since such a light emitting device can emit light with high luminance, it can be applied to lighting devices such as a backlight, an emergency light, and an all-night light of a liquid crystal display device.

[0033] In the case of the eighth invention, the AC power to be applied to the light emitter to make the light emission intensity constant. The pressure is controlled. In such a light-emitting device, since the luminance of the light-emitting body can be increased and the life of the light-emitting device can be increased, the light-emitting device can be practically used as a backlight of a liquid crystal display device, for example.

[0034] According to the ninth aspect of the invention, the means for measuring the light emission intensity of the light emitter and the configuration for controlling the magnitude of the AC voltage to be applied to the light emitter based on the measured light emission intensity are employed. In such a light-emitting device, the luminous body can have a high luminance and a long lifetime, and can be put to practical use as a backlight of a liquid crystal display device, for example.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram showing a configuration of a light emitting device according to Embodiment 1.

FIG. 2 is a graph showing temporal changes in light emission luminance.

FIG. 3 is a chart showing emission luminance after the start time, after 24 hours, and after 100 hours.

FIG. 4 is a schematic configuration diagram showing a configuration of a light emitting device according to Embodiment 2.

FIG. 5 is a graph showing an example of setting an applied voltage.

FIG. 6 is a graph showing temporal changes in light emission luminance.

FIG. 7 is a block diagram showing a configuration of a light emitting device according to Embodiment 3.

Explanation of symbols

[0036] 10 Inorganic EL device

11 袅 [¾ pole

12 Dielectric layer

13 Light emitting layer

14 Dielectric layer

15 Transparent electrode

16 PET film

20 AC power supply

30 Luminescence intensity controller

41 Optical sensor

42 Comparison circuit 43 Emission intensity setting section

44 Inverter circuit

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be specifically described with reference to the drawings illustrating embodiments thereof.

Embodiment 1

FIG. 1 is a schematic configuration diagram showing a configuration of the light emitting device according to Embodiment 1. In the figure, reference numeral 10 denotes an inorganic EL element formed by laminating a back electrode 11, a dielectric layer 12, a light emitting layer 13, a dielectric layer 14, and a transparent electrode 15 in this order. The light emitting device according to the present embodiment is provided with this inorganic EL element 10 and an AC power source 20, and generates EL emission in the light emitting layer 13 by applying an AC voltage to the inorganic EL element 10. It is the composition which makes it. In the present embodiment, the inorganic EL element 10 is sealed with a PET film 16 (PET: Polyethyrene terephthalete) in order to enhance the moisture-proof effect on the inorganic EL element 10. For example, a laminating method can be used for the encapsulation with the PET fine film 16.

Hereinafter, the configuration of the inorganic EL element 10 will be described.

The back electrode 11 is formed by screen-printing conductive carbon on a substrate such as glass or plastic. The electrode may be provided by screen printing using a silver paste in which a fine powder of silver (Ag) is kneaded into an epoxy resin.

The dielectric layers 12 and 14 are formed with a thickness of about 10 μΐη on the upper layer of the back electrode 11 and the upper layer of the light emitting layer 13 by screen printing using barium titanate-containing ink or the like. By forming the dielectric layers 12 and 14, the yield when forming the back electrode 11, the light emitting layer 13, and the transparent electrode 15 is improved, and a stable element that is resistant to dielectric breakdown during light emission is obtained. It is done.

[0041] The light emitting layer 13 is a mixture of the light emitter according to the present invention and a binder made of an ultraviolet curable dielectric material, and is formed on the dielectric layer 12 by screen printing. As the thickness increases, the light emission luminance decreases, and when it is too thin, luminance unevenness occurs. Therefore, in the present embodiment, the light emitting layer 13 having a thickness of 20 to 100 μm is provided.

The transparent electrode 15 is formed on the dielectric layer 14 by screen printing using indium oxide (ITO), zinc oxide (ZnO) or the like. In addition, a silver pace is formed on a part of the surface of the transparent electrode 15. It is good also as a structure which provides separately the current collection electrode formed with the tow.

[0043] Next, a method for producing a light emitter used in the light emitting layer 13 will be described. The manufacturing method is roughly divided into two steps.

[0044] (First step)

Strontium sulfide (SrS), prasedium sulfur (S: Pr ⁺³ ) and strontium carbonate (SrCO ³ ) as main activators, and flux materials such as TaCl, MgCl, NaCl

4 12 2

100g of the blended raw materials are placed in a plastic bottle with 8g of manganese (Mn) and gold (Au) lg, and mechanically mixed for 20 minutes with a stirrer.

[0045] stirred placed in the boat and the resultant mixture in bell jar was evacuated (10- ⁵ Torr), to form a fired cake was fired for about 1 hour at a temperature of 2 250 ° C. Then, after removing the fired cake from the bell jar, it is cooled and washed with deionized water until the pH is 6 or less. Remove the flux material by washing with deionized water and dry.

[0046] (Second step)

At the next stage, the dried calcined cake is pulverized with a vortex theory classifier to a particle size of 5 to 20 μm. Then, put it in a plastic bottle with gallium arsenide (GaAs) and indium phosphide (InP) with a particle size of ~~ 3 μm, and stir and mix with a mechanical stirrer for 20 minutes. The mixture obtained by stirring is placed in a crucible installed in a cylindrical tubular electric furnace, and fired in nitrogen gas with 6% sulfur gas in a quartz tube at a temperature of about 800 ° C for about 3 hours to induce a crystal transition of praseodymium. Let The crystal transition of praseodymium is from the hexagonal system to the cubic system, and its transition temperature is 798 ° C. For this reason, it is fired at a temperature of 798 ° C or higher to induce a crystal transition.

[0047] Then, per 100 g of the calcined product, the mixture is washed with a mixed solution in which 150 ml of glacial acetic acid is mixed with deionized water 11 to remove excess compounds, compatible additives, and impurities. Then wash with deionized water to pH 6 or lower, filter the washed product and dry at about 180 ° C for 2 hours. After cooling the product, sieving with a vortex theory classifier is performed to obtain the luminescent material of the present invention.

[0048] Next, characteristics of the light emitter manufactured as described above will be described.

Fig. 2 is a graph showing the change in emission luminance over time, and Fig. 3 shows the start time, 24 hours later, It is a graph which shows the light-emitting luminance after 100-hour progress. The horizontal axis of the graph shown in FIG. 2 represents the elapsed time from the time when the AC voltage was applied (start time), and the vertical axis represents the luminance of the light emitting layer 13. Here, the curve with the label of Sample A is based on a light-emitting body manufactured from a conventional inorganic EL material containing ZnS as a base material and Cu and C1 added thereto. The curves labeled Sample B and Sample C are both produced by the force S of the illuminant of the present invention, and for Sample B, the process before adding GaAs and InP (first process) is the final process. The light-emitting body, sample C, is a light-emitting body manufactured using a material that has been baked in a nitrogen atmosphere containing 6% sulfur gas with GaAs and InP added.

[0049] As shown in the graph of FIG. 2, the illuminant of sample A had a luminance of 691 cdZm ² when an AC voltage was applied, and the luminance may monotonously decrease with the elapsed time. I understand. The half-life of sample A that can be read from the graph is about 120 hours. The illuminant of Sample B had a luminance of 2800 cd / m ² when an AC voltage was applied, and it was found that the luminance could be improved by a factor of about 4 over conventional inorganic EL materials. The half-life of Sample B, which can be read from the graph power, is about 140 hours. The luminance of Sample C's illuminant can be further improved, and it has a luminance of 4411 / m ² at the start of application of AC voltage, which is about 6 times the luminance of conventional inorganic EL materials. did. The half-life of sample C, which can be read from the graph, was about 185 hours, and it was found that the lifetime of the device could also be improved.

Embodiment 2

[0050] In the first embodiment, a constant AC voltage is applied to the inorganic EL element 10, but the applied AC voltage is controlled to make the emission intensity (luminance) of the inorganic EL element 10 substantially constant. You may make it keep.

FIG. 4 is a schematic configuration diagram showing a configuration of the light emitting device according to Embodiment 2. The light emitting device according to the present embodiment includes an inorganic EL element 10 and a light emission intensity control unit 30. The inorganic EL element 10 is the same as that described in Embodiment 1, and is formed by laminating the back electrode 11, the dielectric layer 12, the light emitting layer 13, the dielectric layer 14, and the transparent electrode 15 in this order. It is a thing. The inorganic EL element 10 is sealed with a PET film 16.

[0052] The emission intensity control unit 30 controls the inorganic E element 10 in order to keep the emission intensity of the inorganic EL element 10 substantially constant. Controls the voltage applied to L element 10. Therefore, the emission intensity control unit 30 includes an AC power source connected to the inorganic EL element 10, a memory that stores setting values for applied voltage, and a microcomputer that drives the AC power source according to the setting values stored in the memory ( (Not shown).

FIG. 5 is a graph showing an example of setting the applied voltage. The horizontal axis represents the elapsed time from the time when the AC voltage is applied to the light emitting layer 13, and the vertical axis represents the set value for the applied voltage. In this example, the applied voltage at the start time is set to VI (for example, 180V). Then, the applied voltage is monotonously increased until the elapsed time becomes hi (for example, 120 hours), and when the elapsed time becomes hi, the applied voltage is set to V2 (for example, 240V). It is set to keep the applied voltage at V2. The above-mentioned memory stores the applied voltage (set value) specified for the elapsed time, and the microcomputer reads the set value from the memory based on the output of the built-in timer (not shown) and reads the set value. The AC power supply is controlled according to the value. Note that the memory may store the values on the graph as discrete functions or as a function of the elapsed time.

Next, luminance characteristics of the light emitting device when the applied voltage is variable will be described. Figure 6 is a graph showing the time variation of the emission brightness. The horizontal axis represents the elapsed time from the time when the AC voltage is applied (start time), and the vertical axis represents the luminance of the light emitting device according to Embodiment 3. As a comparison object, the luminance change with time when a constant AC voltage is applied to the sample C described in Embodiment 1 is also drawn. Both have the same illuminant used for the luminescent layer 13, but it has been found from the results of investigations by the inventors that a phenomenon is observed in which the luminance is stabilized by optimizing the applied voltage. That is, by controlling the applied voltage as shown in FIG. 5, the emission luminance of the inorganic EL element 10 enters a stable state in about 120 hours, and thereafter no fluctuation in the emission luminance is observed for at least 1000 hours. I understood. The half-life of EL emission estimated from the decay prediction curve based on the graph in Fig. 6 was 20000 hours or more, indicating that it was possible to manufacture a light-emitting device with a practically sufficient lifetime.

Embodiment 3

In Embodiment 2, the AC voltage applied to inorganic EL element 10 is set according to a predetermined set value. However, it is also possible to measure the intensity of light emitted from the inorganic EL element 10 and determine the voltage applied to the inorganic EL element 10 based on the measured value.

FIG. 7 is a block diagram showing a configuration of the light emitting device according to Embodiment 3. The light emitting device according to the present embodiment includes an optical sensor 41, a comparison circuit 42, a light emission intensity setting unit 43, and an inverter circuit 44 in addition to the inorganic EL element 10 described in the first embodiment.

The optical sensor 41 includes a photodiode or the like not shown in the drawing in order to measure the intensity of light emitted from the inorganic EL element 10. The optical sensor 41 converts the photocurrent flowing through the photodiode into a voltage when irradiated with light, and outputs the value (voltage value) to the comparison circuit 42.

The emission intensity setting unit 43 determines a set value for the emission intensity of the inorganic EL element 10. This set value is, for example, a value that is arbitrarily set when the product is shipped or in the user's installation environment. The comparison circuit 42 is a circuit that compares the voltage value output from the optical sensor 41 with the set value in the light emission intensity setting unit 43 and changes the output according to the comparison result. The inverter circuit 44 is a power supply circuit for driving the inorganic EL element 10, and the applied voltage at the time of driving is controlled by the output of the comparison circuit 42.

Next, the operation of the light emitting device having the above-described configuration will be described. When the inorganic EL element 10 emits light at a certain intensity, the optical sensor 41 outputs a voltage value (referred to as S1) corresponding to the intensity to the comparison circuit 42. The comparison circuit 42 compares the voltage value S1 with the set value (referred to as S2) set in the emission intensity setting unit 43. As a result, when it is determined that the voltage value S1 is smaller than the set value S2, it can be determined that the light emission intensity is weak. Therefore, in order to increase the voltage applied to the inorganic EL element 10, the output of the comparison circuit 42 is increased. At this time, the inverter circuit 44 operates to increase the emission intensity of the inorganic EL element 10.

[0060] On the other hand, if the comparison circuit 42 compares the voltage value S1 of the light sensor 41 with the setting value S2 of the light emission intensity setting unit 43 and determines that the voltage value S1 is larger than the setting value S2, Since it can be determined that the emission intensity of the inorganic EL element 10 has increased due to the rise or the heat generation of the light emitting device itself, the output of the comparison circuit 42 is reduced in order to reduce the voltage applied to the inorganic EL element 10. At this time, the inverter circuit 44 operates so as to weaken the emission intensity of the inorganic EL element 10. As described above, the light emitting device of the present embodiment operates so that the voltage value S1 of the optical sensor 41 and the set value S2 of the light emission intensity setting unit 43 are equalized by the feedback operation. As a result, the light emission intensity (luminance) of the inorganic EL element 10 is kept substantially constant, and a long-life light-emitting device is configured as in the second embodiment.

Claims

The scope of the claims

[1] A method of manufacturing a light emitter using a rare earth sulfide as a base material,

A mixture of the base material and an activator that includes Pr, Mn, and Au and activates the base material is generated, and the generated mixture is heated to activate the base material. A method for manufacturing a luminous body.

[2] The method for manufacturing a light emitter according to claim 1, wherein the rare earth sulfide is SrS.

[3] The method according to claim 1 or 2, wherein after activating the base material, GaAs and InP are added, and firing is performed at a temperature of 798 ° C or higher in a nitrogen atmosphere containing sulfur gas. The manufacturing method of the light-emitting body as described.

[4] In a light emitter using a rare earth sulfide as a base material,

A light emitter comprising Pr, Mn, and Au added to the base material.

[5] The light emitter according to claim 4, wherein the rare earth sulfide is SrS.

[6] The light emitter according to claim 4 or 5, wherein GaAs and InP are further added.

[7] A light-emitting device comprising: the light-emitting body according to any one of claims 4 to 6; and means for applying an alternating voltage to the light-emitting body.

8. The light emitting device according to claim 7, further comprising means for controlling the magnitude of the AC voltage so as to make the light emission intensity of the light emitter constant.

[9] It comprises: means for measuring the light emission intensity of the light emitter; and means for controlling the magnitude of the AC voltage to be applied to the light emitter based on the light emission intensity measured by the means. The light emitting device according to claim 7.